Study On Wetting Deformation Law And Numerical Simulation Method Of Rockfill In Earth-rock Dam

Rockfill,as an important part of earth-rock dam,will produce wetting deformation due to water impregnation during dam impoundment,which will cause obvious settlement and horizontal displacement of upstream side of the dam body.It is easy to cause uncoordinated deformation between the top of the dam and the top of the upper and lower dam slopes,and then crack will occur,endangers the safety of the dam.Therefore,it is of great engineering application value to study the wetting deformation characteristics of rockfill and develop the numerical simulation method for the deformation of earth-rock dam.Combined with the wetting test of different scholars,this paper analyzes the wetting deformation rule of rockfill material,and puts forward a "single line method" wetting test model.Then,combined with the mechanism and process of rockfill humidification deformation,the method of using the "double line method" and "single line method" humidification test model to simulate the humidification deformation of earth-rock dam in ABAQUS is studied.Finally,the actual impoundment process of the dam is simulated and analyzed numerically.The main results of this paper are as follows:(1)The wetting deformation law of rockfill is studied.In the process of humidification,the axial strain caused by confining pressure and the confining pressure satisfy the power function relationship.The humidification volume change caused by confining pressure is approximately three times of the axial change.The axial change caused by bias pressure has a hyperbolic relationship with the stress level,and the humidification volume change caused by bias pressure has a linear relationship with the axial change.In addition,in the study of the wetting deformation law,it is found that there is a critical point of stress level in the process of wetting.When the critical point is exceeded,the increase rate of the axial and volumetric changes of wetting accelerates,and the sample is quickly destroyed.(2)A 9-parameter wetting deformation model is proposed.In the model,the humidification axial strain is divided into the strain caused by confining pressure and the strain caused by deviatoric stress,and the humidification volumetric strain is also divided into the strain caused by confining pressure and the strain caused by deviatoric stress,so that the relationship between each part is clearer and easier to determine.The results of the model are in good agreement with the experimental data of different scholars.(3)In ABAQUS software,the "double-line method" is used to calculate the wetting deformation of earth-rock dam by using the dry-wet two sets of parameters of Duncan-Zhang E-B model,and the "single-line method" is used to calculate the wetting deformation of earth-rock dam by using the wetting deformation model in this paper.The idea of "double line method" is to calculate the deformation of earth-rock dam by using two sets of dry and wet parameters,and the difference between the former and the latter is the wetting deformation value.The basic idea of the "single line method" is to constrain the displacement of the humidification element,and convert the stress reduction or strain increase caused by humidification calculated by the "initial stress method" or "initial strain method" into virtual equivalent node load,which is applied to the dam together with water pressure and buoyancy force to simulate the humidification deformation.(4)Using "double line method" and "single line method",the numerical calculation and analysis of stress and deformation of an example dam in the process of impoundment are carried out,and the wetting deformation calculation results which accord with the actual engineering are obtained,and the correctness of the method presented in this paper is proved.